A 66-year-old woman, 155 cm, weighing 65 Kg, had mildly elevated transaminases, within 100 U/L of ALT, during her annual physical examination, and ultrasound also suggested fatty liver, but did not pay much attention to it. 5 years ago, she was diagnosed with cirrhosis by ultrasound in our outpatient clinic, and other chronic liver diseases such as viral hepatitis and autoimmune hepatitis were excluded. Finally, he was defined as unexplained cirrhosis. The etiology was unknown making it difficult to treat further, this time further examination and finally liver puncture was recommended. The pathological results are as follows. Surprisingly, it was cirrhosis caused by steatohepatitis (NASH). Even I was surprised how such a serious result could be achieved when the ALT was only 50U/L this time. In fact, there is a lack of proper understanding of fatty liver both among the general public and lay doctors. Even the author, who has been engaged in liver disease for more than 20 years, used to mistakenly believe that fatty liver is generally not too bad in terms of results, but in recent years, more and more data, as well as cases like this, have reminded me time and again that the consequences of non-alcoholic fatty liver are very serious, just that we usually do not have in-depth examination! Non-alcoholic fatty liver disease (NAFLD) is a complex disease closely related to genetic susceptibility, caloric excess, intestinal microecological imbalance, insulin resistance and oxidative stress, and the disease spectrum includes non-alcoholic simple fatty liver (NAFL), non-alcoholic steatohepatitis (NASH), and NASH cirrhosis and cryptogenic cirrhosis. NAFL is generally very unlikely to develop into cirrhosis as well as liver cancer, but nearly 10-25% of NAFL will develop into NASH. NASH can become a pathological factor like chronic hepatitis B and C driving liver damage and progressing to cirrhosis and liver cancer, and liver aspiration pathology is not recommended for all NAFL The problem is that current liver function, ultrasound, CT, etc. do not differentiate between NAFL and NASH. drug therapy is not recommended for NAFL and NASH, and lifestyle interventions: diet moderation, increased exercise, and modification of maladaptive behaviors are the first-line treatment options for NAFLD and its coexisting cardiovascular and metabolic risks. patients with NAFLD/NASH need to reduce daily dietary calories by 25% and limit monosaccharides, disaccharides, and saturated and trans fats. Aim for a weight loss of 5% to 10% in about 1 year. The degree of improvement in insulin resistance and liver histology is proportional to the amount of body mass loss, and effective reversal of NASH is only possible when a 7% reduction in body mass is maintained for more than 48 weeks.